A membrane-less visible-light responsive micro photocatalytic fuel cell with the laterally-arranged CdS/ZnS-TiO2 photoanode and air-breathing CuO photocathode for simultaneous wastewater treatment and electricity generation

摘要

Photocatalytic fuel cell (PFC) is a promising wastewater treatment technology, which cannot only purify wastewater but also generate electricity using solar energy. In this study, a membrane-less visible-light responsive micro PFC was developed, where the CdS/ZnS-TiO2 deposited on a conductive glass as a photoanode and CuO deposited on the porous carbon paper as an air-breathing photocathode were laterally arranged. Such design allows for both the photoanode and photocathode to be irradiated simultaneously from one side and enhances photon and mass transport. It was found that the developed micro PFC with dual photoelectrodes well responded to light illumination and exhibited good long-term performance. Experimental results also showed that upgrading the light intensity and methanol and electrolyte concentrations could improve the discharging performance because of larger amount of generated electron-hole pairs and more hole scavengers resulting from the enhanced transport. Besides, it was also found that although the increase of the liquid flow rate from extremely low rate to a moderate one caused the residence time to be lowered, positive contribution resulting from enhanced mass transport was more significant, leading to the improved performance. However, too high liquid flow rate resulted in critical low residence time, which made the discharging performance worse. The feasibility of the developed micro PFC with dual photoelectrodes toward the applications of using solar energy to remove organic pollutants contained in wastewater and simultaneously generate electricity is demonstrated in this work.